AIRCRAFT TURBOMACHINE MECHANICAL GEARBOX SATELLITE BRACKET

Abstract

A planet carrier (213) for a mechanical gearbox (10, 110) of an aircraft turbomachine (1), comprising: - a first disk (236) centered on a first axis (X) and extending perpendicularly to this first axis (X), this first disk (236) having first orifices (292) centered respectively on second axes (Y) parallel to this first axis (X), - a second disk (238) centered on the first axis (X) and extending parallel to and at a distance from the first disk (236), this second disk (238) having second orifices (294) which are respectively centered on the second axes (Y), the number of second orifices (294) being equal to the number of first orifices (292), - bridges (296) which extend between the first and second disks (236, 238) and connect them together, the bridges (296) being formed in one piece with the first and second disks (236, 238). Figure for the abbreviation: Figure 6

Description

Title of the invention: PLANET CARRIER FOR MECHANICAL REDUCER OF AIRCRAFT TURBOMACHINE Technical field of the invention

[0001] The present invention relates to a planet carrier and a mechanical reducer for an aircraft turbomachine, as well as a turbomachine comprising such a planet carrier or such a reducer. Technical approval plan

[0002] The state of the art includes in particular documents FR-A1-2 987 416, FR-Al-2 853 382, ​​FR-A1-3 041 054, FR-A1-3 073 915, FR-A1-3 084 428.

[0003] The role of a mechanical reducer is to modify the speed ratio and the torque between the input axis and the output axis of a mechanism.

[0004] New generations of dual-flow turbomachines, particularly those with a high bypass ratio, include a mechanical reducer to drive the shaft of a fan (also called a "fan"). Usually, the reducer aims to transform the so-called fast rotation speed of the shaft of a power turbine into a slower rotation speed for the shaft driving the fan.

[0005] Such a reducer comprises a central pinion, called a sun gear, a crown gear and pinions called satellites, which are engaged between the sun gear and the crown gear. The satellites are held by a frame called a planet carrier. The sun gear, the crown gear and the planet carrier are planetary gears because their axes of revolution coincide with the longitudinal axis of the turbomachine. The satellites each have a different axis of revolution and are equally distributed over the same operating diameter around the axis of the planetary gears. These axes are parallel to the longitudinal axis of the turbomachine.

[0006] There are several gearbox architectures. In the state of the art of dual-flow turbomachines, the gearboxes are of the planetary or epicyclic type. In other similar applications, there are so-called differential or "compound" architectures.

[0007] - on a planetary reducer, the planet carrier is fixed and the crown constitutes the output shaft of the device which rotates in the opposite direction of the solar.

[0008] - on an epicyclic reducer, the crown is fixed and the planet carrier constitutes the output shaft of the device which rotates in the same direction as the solar.

[0009] - on a differential reducer, no element is fixed in rotation. The crown rotates in the opposite direction of the solar and the satellite carrier.

[0010] The reducers can be composed of one or more meshing stages. This meshing is ensured in different ways such as by contact, by friction or even by magnetic field. There are several types of contact meshing such as straight or herringbone teeth.

[0011] The planet carrier may be in one piece or in the form of a cage and a cage carrier. The cage comprises an internal cavity in which the sun gear, the satellites and the guide bearings for these satellites are housed. The sun gear comprises internal splines for coupling to a first shaft of the turbomachine and the cage carrier comprises a cylindrical portion comprising external splines for coupling to another shaft.

[0012] The connection of the cage to the cage holder is generally rigid. Alternatively, a technology may be envisaged in which the cage is connected to the cage holder by “flexible” connections, such as described in document FR-A1-2 853 382. In such a case, the cage holder comprises an annular row of axial fingers which carry first connection elements. These first connection elements cooperate with second connection elements mounted in housings of the cage to form the flexible connections between the cage holder and the cage, which allow at least one degree of freedom.

[0013] In operation, the planet carrier is subjected to forces which tend to deform it. This is the case for a single-piece planet carrier or a cage and cage carrier type. These deformations generate tilting of the planets, leading to degradation of the meshing, and risks of the appearance of an asymmetrical oil film in the case of the use of plain or hydrodynamic bearings for guiding the planets, or risks of generating tilting of the rollers in the case of the use of rolling bearings for guiding the planets. These forces and deformations must be rebalanced in order to limit or even cancel these effects.

[0014] Furthermore, the planet carrier contains orifices to accommodate the ends of the guide bearings of the satellites. These orifices can be machined and the machining tolerances can generate dimensional and positional defects of these orifices. To reduce the positional tolerances of these orifices, they can be ground, which is restrictive from an industrial point of view. It is also possible to choose the material of the planet carrier to reduce its stiffness, for example with titanium or aluminum instead of steel. However, this also generates additional constraints (machinability, mechanical strength, tribological behavior, etc.).

[0015] Positioning defects in the bearings of the satellites, whether plain or rolling bearings, and therefore in the satellites themselves, generate an internal overload in the reducer on at least one of the satellites. This may require oversizing the components of the reducer (teeth and plain and rolling bearings) and therefore penalize the mass and performance of the reducer.

[0016] The present invention provides a solution to this need, which is simple, effective and economical. Summary of the invention

[0017] The invention relates to a planet carrier for a mechanical reducer of an aircraft turbomachine, this planet carrier comprising:

[0018] - a first disc centered on a first axis or central axis and extending perpendi cularly to this first axis, this first disc comprising first orifices or bearing orifices centered respectively on second axes or bearing axes which are distributed around the first axis and parallel to this first axis,

[0019] - a second disc centered on the first axis and extending parallel and at a distance of the first disc, this second disc comprising second orifices or bearing orifices which are respectively centered on the second axes, the number of second bearing orifices being equal to the number of first bearing orifices,

[0020] - bridges which extend between the first and second discs and connect them together them.

[0021] The principle of the invention is to locally soften the planet carrier, in particular in the vicinity of the orifices for receiving the satellite axes. Indeed, the internal overload is due to the position tolerances of the orifices of the satellite axes. A satellite offset from its perfect nominal position can undergo a positive or negative load difference depending on the direction of the offset, which can be up to 10% or more. This effect is amplified by the local stiffness of the planet carrier between two successive satellites. Thus, the lower this stiffness, the lower this overload is also. The reduction in the design load makes it possible to obtain a significant weight saving.

[0022] According to a first aspect of the invention, at least one of the discs comprises alternating concave and convex curved portions on each of the inner and outer peripheral edges of the disc, the convex curved portions of the inner peripheral edge and the concave curved portions of the outer peripheral edge being aligned radially with respect to the central axis and extending respectively radially inside and radially outside the bearing holes of the disc, and the concave curved portions of the inner peripheral edge and the convex curved portions of the outer peripheral edge being aligned radially with respect to the central axis and the numbers of concave and convex curved portions of the inner and outer peripheral edges of the disc being equal to the number of bearing holes of this disc.

[0023] The planet carrier according to the invention is thus configured to improve its operating behavior and in particular its resistance to deformations caused by the transmission of forces. The impact on the bearings, such as their misalignments or their asymmetries, is thus reduced.

[0024] This is made possible by the particular shapes of the peripheral edges internal and external of the or each disc. Each of these edges includes alternating concave and convex curved portions. The number of concave curved portions of the internal peripheral edge is equal to the number of convex curved portions of this edge, and is also equal to the number of orifices of this disc. The number of concave curved portions of the external peripheral edge is equal to the number of convex curved portions of this edge, and is also equal to the number of orifices of this disc.

[0025] The concave curved portions of the inner peripheral edge and the convex curved portions of the outer peripheral edge are radially aligned and located between the holes of the disc. The convex curved portions of the inner peripheral edge and the concave curved portions of the inner peripheral edge are radially aligned and located respectively radially on either side of the holes of the disc.

[0026] This first aspect allows a reduction in the thicknesses or ligaments of material at the planet carrier / bearing axis interface in the radial planes. Each ligament can be reduced to the minimum necessary to hold the receiving orifice of the corresponding bearing.

[0027] According to a second aspect of the invention, the bearing orifices of at least one of the discs are distributed in pairs, each pair of bearing orifices comprising two circumferentially adjacent bearing orifices, the or each disc comprising pairs of bearing orifices comprising, between each pair of bearing orifices, a first through hole which is intersected by a first plane extending radially with respect to the central axis and located at equal distances from the bearing orifices of the pair, and which is intersected by a second plane passing through the bearing axes of this pair of bearing orifices, the first plane being a first plane of symmetry for the hole.

[0028] The planet carrier according to the invention is thus configured to improve its operating behavior and in particular its resistance to deformations caused by the transmission of forces. The impact on the bearings, such as their misalignments or their asymmetries, is thus reduced.

[0029] The first hole has only a lightening function and has no additional or other function, such as a fixing hole for example. Each first hole is therefore preferably smooth, i.e. not tapped.

[0030] The second aspect of the invention makes it possible to soften the zones between the orifices, halfway between these orifices. A zone of flexibility is thus added in the tangential plane arranged equidistant from the two orifices. The optimum zone is located at the intersection of the plane passing through the two centers of the orifices and the plane of symmetry of the two orifices. The presence of the holes at a distance from the orifices also makes it possible to avoid excessive local deformations which could generate fretting between bearings and carriers. tellites.

[0031] Both aspects of the invention and their features can be combined together.

[0032] The benefits provided by the invention are numerous and include:

[0033] - better accommodation of the movements applied to the interfaces of the reducer,

[0034] - a reduction in satellite overloads,

[0035] - a reduction in the mass of the planet carrier,

[0036] - a gain in the dynamic behavior of the planet carrier,

[0037] - etc.

[0038] The present invention is compatible: - a single-stage or multi-stage reducer; - a planetary, epicyclic or differential reducer; - straight, helical or herringbone teeth; - any type of single-piece or cage and cage-holder type planet carrier; - all types of satellite guide bearings, such as rolling elements or hydrodynamic.

[0039] The planet carrier according to the invention may comprise one or more of the following characteristics, taken in isolation from one another, or in combination with one another:

[0040] — the bridges are formed in one piece with the first and second discs; - the convex curved portions of the inner peripheral edge extend around the bearing axes of the bearing holes of the disc; - the convex curved portions of the inner peripheral edge have an angular extent around the central axis, which is less than an angular extent around the central axis of the concave curved portions of the inner peripheral edge; - the concave curved portions of the outer peripheral edge have an angular extent around the central axis, which is less than or equal to an angular extent around the central axis of the convex curved portions of the outer peripheral edge; - the convex curved portions of the inner peripheral edge have an angular extent around the first axis, which is equal to + / -10% of an angular extent around the central axis of the concave curved portions of the outer peripheral edge, and / or the concave curved portions of the inner peripheral edge have an angular extent around the central axis, which is equal to + / -10% of an angular extent around the central axis of the convex curved portions of the outer peripheral edge; - the apexes of the convex curved portions of the inner peripheral edge are located on a circumference centered on the central axis which has a first diameter, and the apexes of the concave curved portions of the inner peripheral edge are located on another circumference centered on the central axis which has a second diameter, half of the difference between the second and first diameters being less than or equal to a minimum radial thickness of material of the disc around its bearing orifices and at the inner peripheral edge; - the apexes of the concave curved portions of the outer peripheral edge are located on a circumference centered on the central axis which has a first diameter, and the apexes of the convex curved portions of the outer peripheral edge are located on another circumference centered on the central axis which has a second diameter, half of the difference between the second and first diameters being greater than or equal to a minimum radial thickness of material of the disc around its bearing orifices and at the outer peripheral edge; - the convex curved portions of the inner peripheral edge have a radius of curvature which is less than the radius of curvature of the concave curved portions of the inner peripheral edge; - the concave curved portions of the outer peripheral edge have a radius of curvature which is equal to + / -10% of the radius of curvature of the convex curved portions of the outer peripheral edge; - the planet carrier has a maximum radial dimension at the holes in the disc which is less than a maximum radial dimension of the planet carrier between the holes; - the concave curved portions of the internal peripheral edge are all and entirely located on the same circumference centered on the first axis; - the convex curved portions of the external peripheral edge are all and entirely located on the same circumference centered on the first axis;

[0041] — the first plane is also a plane of symmetry for the orifices of the pair; - the second plane is also a plane of symmetry for the hole; - each of the holes has a circular shape centered on the point of intersection between the first and second planes; - each of the holes has an elliptical circular shape which includes a larger transverse dimension extending along said first plane; - each of the holes has a rectangular shape with rounded corners; - each of the holes includes a radially internal edge which is curved convex around the first axis, a radially outer edge that is curved concave about the first axis, a first side edge which is convexly curved about the second axis of a first of the orifices of the pair, and a second side edge which is convexly curved about the second axis of a second of the orifices of the pair; - the or each disc comprising pairs of bearing holes comprises, circumferentially between each pair of bearing holes, at least one additional through hole which is located radially above or below the first hole, and which is cut by said first plane; - the first hole and the or each additional hole have the same shape and the same dimensions; - the or each disc comprising pairs of bearing orifices comprises, circumferentially between each pair of bearing orifices, at least one through-hole, said first plane also being a plane of symmetry of this hole; - the or each disc has a thickness of material measured in the radial direction relative to the central axis, between an internal peripheral edge of the disc, and the first hole, which is less than a second thickness of material measured in the same direction, between the first hole and the light;

[0042] — the planet carrier is of the monoblock type;

[0043] — the planet carrier is of the cage and cage carrier type, the two discs and the bridges forming the cage.

[0044] The present invention also relates to a mechanical reducer for an aircraft turbomachine, comprising a planet carrier as described above, the reducer further comprising:

[0045] - a solar which is centered on the central axis and which is mounted between the discs of the carrier- satellites,

[0046] - satellites which are centered on the bearing axes and mounted between the discs of the planet carriers, the satellites being guided in rotation by bearings housed respectively in the first and second bearing holes of the discs, and

[0047] - a crown being centered on the central axis and extending around the solar and sa tellites, the satellites being meshed with the solar and the corona.

[0048] The invention further relates to a turbomachine, in particular for an aircraft, comprising a reduction gear as described above. Brief description of the figures

[0049] Other characteristics and advantages will emerge from the following description of a non-limiting embodiment of the invention with reference to the appended drawings in which:

[0050] [Fig.l] [Fig.l] is a schematic axial sectional view of a turbomachine using the invention;

[0051] [Fig.2] [Fig.2] is a schematic axial sectional view of a mechanical reducer

[0052] [Fig.3] [Fig.3] is a perspective view of a cage and cage holder assembly forming a mechanical reducer planet carrier;

[0053] [Fig.4] [Fig.4] is a partial axial sectional view of a part of the carrier tellites of [Fig.3];

[0054] [Fig.5] [Fig.5] is a detail view of [Fig.4];

[0055] [Fig.6] [Fig.6] is a schematic front view of the planet carrier of [Fig.3];

[0056] [Fig.7] [Fig.7] is a view similar to that of [Fig.6] and illustrates a mode of rea installation of a satellite carrier according to the invention;

[0057] [Fig.8] [Fig.8] is an enlarged view of part of [Fig.7];

[0058] [Fig.9] [Fig.9] is a view similar to that of [Fig.6] and illustrates another mode of producing a satellite carrier according to the invention;

[0059] [Fig. 10] [Fig. 10] is an enlarged view of part of [Fig.9];

[0060] [Fig. 11] [Fig. 11] is a view similar to that of [Fig. 10] and illustrating a alternative embodiment of the invention;

[0061] [Fig.12] [Fig.12] is a view similar to that of [Fig.10] and illustrating another alternative embodiment of the invention;

[0062] [Fig. 13] [Fig. 13] is a view similar to that of [Fig. 10] and illustrating another alternative embodiment of the invention. Detailed description of the invention

[0063] [Fig.l] describes a turbomachine 1 which comprises, in a conventional manner, a fan S, a low-pressure compressor 1a, a high-pressure compressor 1b, an annular combustion chamber 1c, a high-pressure turbine 1d, a low-pressure turbine 1c and an exhaust nozzle 1h. The high-pressure compressor 1b and the high-pressure turbine 1d are connected by a high-pressure shaft 2 and form with it a high-pressure (HP) body. The low-pressure compressor 1a and the low-pressure turbine 1c are connected by a low-pressure shaft 3 and form with it a low-pressure (LP) body.

[0064] The blower S is driven by a blower shaft 4 which is connected to the LP shaft 3 by means of a mechanical reducer 10. This reducer 10 is generally of the planetary or epicyclic type.

[0065] Although the following description relates to a planetary or epicyclic type reducer, it also applies to a mechanical differential in which its three essential components, namely the planet carrier, the crown and the sun gear, are rotating, the rotation speed of one of these components depending in particular on the difference in speeds of the other two components.

[0066] The reducer 10 is positioned in the upstream part of the turbomachine. A fixed structure comprising schematically, here, an upstream part 5a and a downstream part 5b which composes the motor casing or stator 5 is arranged so as to form an enclosure E surrounding the reducer 10. This enclosure E is here closed upstream by seals at the level of a bearing allowing the fan shaft 4 to pass through, and downstream by seals at the level of the passage of the LP shaft 3.

[0067] [Fig. 1] shows a part of a reducer 10 which can take the form of different architectures depending on whether certain parts are fixed or rotating. At the input, the reducer 10 is connected to the LP shaft 3, for example via splines 7. Thus, the LP shaft 3 drives a planetary pinion called the sun gear 11. Conventionally, the sun gear 11, the axis of rotation of which coincides with the axis X of the turbomachine 1, drives a series of pinions called satellites 12, which are equally distributed circumferentially on the same diameter around the axis of rotation X. This diameter is equal to twice the operating center distance between the sun gear 11 and satellites 12. The number of satellites 12 is generally defined between three and seven for this type of application.

[0068] The set of satellites 12 is held by a frame called a planet carrier 12. Each satellite 12 rotates around its own Y axis, and meshes with the crown 14.

[0069] At the output of reducer 10, we have: • In an epicyclic configuration, the set of satellites 12 rotates the planet carrier 13 around the axis X of the turbomachine. The crown 14 is fixed to the engine casing or stator 5 via a crown carrier 15 and the planet carrier 12 is fixed to the fan shaft 4. • In a planetary configuration, all of the planet gears 12 are held by a planet carrier 12 which is fixed to the engine casing or stator 5. Each planet gear drives the crown which is attached to the fan shaft 4 via a crown carrier 15.

[0070] Each satellite 12 is mounted to rotate freely using a bearing 8 around a Y axis. The Y axes of rotation of the satellites 12 are distributed around the X axis and parallel to this X axis. The bearings 8 are for example of the rolling bearing type or hydrodynamic bearings. Each bearing 8 is mounted on a physical axis 13a of the planet carrier 12 and all these physical axes 13a are positioned relative to each other using one or more structural frames of the planet carrier 12. There is a number of physical axes 13a and bearings 8 equal to the number of satellites 12. For reasons of operation, assembly, manufacturing, control, repair or replacement, the axes 13a and the frame can be separated into several parts.

[0071] For the same reasons cited above, the teeth of a reducer can be separated into several helices. In our example, we detail the operation of a 10 multi-helix reducer with a crown separated into two half-crowns: • A front half-crown 14a consisting of a rim 14aa and a half-fixing flange 14ab. On the rim 14aa is the front helix of the reduction gear teeth. This front helix meshes with that of the satellite 12 which meshes with that of the solar 11. • A rear half-crown 14b consisting of a rim 14ba and a half-fixing flange 14bb. On the rim 14ba is the rear helix of the reduction gear teeth. This rear helix meshes with that of the satellite 12 which meshes with that of the solar 11.

[0072] The half-flange 14ab of the front crown 14a and the half-flange 14bb of the rear crown 14b form the fixing flange 14c of the crown. The crown 14 is fixed to the crown carrier 15 by assembling the fixing flange 14c of the crown and the fixing flange 15a of the crown carrier using a bolted assembly for example. In the following, a half-flange may be called a flange.

[0073] The arrows in [Fig.l] describe the oil routing in the reducer 10. The oil arrives in the reducer 10 from the stator part 5 in the distributor 16 by different means which will not be specified in this view because they are specific to one or more types of architecture. The distributor 16 is separated into two parts, generally each repeated by the same number of satellites. The injectors 17a have the function of lubricating the teeth, and the arms 17b have the function of lubricating the bearings 8. The oil is brought towards the injector 17a to exit through the end 17c in order to lubricate the teeth. The oil is also supplied to each arm 17b and circulates via the supply port 17d of the bearing 8. The oil then circulates through the axis 13a in one or more buffer zones 13b and then exits through orifices 13c in order to lubricate the bearings 8 of the satellites.

[0074] The planet carrier 13 of [Fig.2] is formed from a single piece in the example shown.

[0075] In Figures 3 to 5, the elements already described in the above are designated by the same references increased by one hundred.

[0076] Figures 3 to 5 represent a particular technology of planet carrier 113, this planet carrier comprising a cage 120 and a cage carrier 122 connected by ball joints.

[0077] The cage 120 comprises two radial annular discs or walls 136, 138 which are parallel to each other and perpendicular to the axis X, as well as a cylindrical wall 140 which extends between the external peripheries of these disc walls 136, 138.

[0078] The cylindrical wall 140 is here of the double-skin type and comprises an external skin 140a interrupted by the lights 143 and an internal skin 140b interrupted by the same lights 143. The external skin 140a separated by five lights 143 forms five external bridges and the internal skin 140b separated by five lights 143 forms five internal bridges. Each pair of lower and upper bridges forms a yoke to accommodate the finger 182 of the cage holder 122. In other words, the bridges of each pair define between them a housing 180 for receiving a finger 182 of the cage holder 122. The bridges provide the structural connection between the walls 136 and 138. Oblong-shaped lights 180a are made in at least one of the walls 136 and 138 so as to allow the finger 182 to pass between the internal and external bridges. These lights 180a open into the housings 180.

[0079] The cage 120 thus comprises an annular row of housings 180. These housings 180 receive the axial fingers 182 secured to a substantially radial annular wall 182a of the cage holder 122. The wall 182a is located at an axial end of the cage holder 122. The fingers 182 extend axially from the wall 182a and are engaged by axial translation in the housings 180.

[0080] Each finger 182 comprises, substantially in its middle, a ring 184 for mounting the ball joint 186 intended to be crossed by a cylindrical pin 188 carried by the cage 120.

[0081] The ring 184 has a substantially radial orientation relative to the axis X. It has a generally cylindrical shape. The cage 120 and the ball joint 186 have a thickness, measured in a radial direction relative to the axis X, which is less than the inter-bridge distance or the radial thickness of the oblong slot 180a, so as to be able to be engaged in this housing concomitantly with the finger 182 supporting these parts.

[0082] Each housing 180 is crossed by a pin 188 which has a substantially radial orientation relative to the axis X. Each pin 188 comprises a cylindrical body 188a connected at an axial end, here radially internal, to an external annular collar 188b. The pin 188 is here engaged by radial translation from the inside through radial orifices of the bridges, its collar 188b being intended to come into radial support on a flat face 191 of the external bridge of the cage 120. After insertion of the pin 188 into the orifices of the bridges, until the collar 188b is pressed against the external bridge, the collar 188b is fixed to this bridge for example by screwing.

[0083] [Fig. 6] shows a detail of the discs or walls 136, 138 of the planet carrier 113. In these figures, it can be seen that each of the walls 136, 138 comprises first orifices 192, 174 centered respectively on the Y axes of rotation of the satellites of the reducer. The orifices 192, 194 of each of the walls 136, 138 are here five in number in the example shown. The orifices 192 and 194 do not necessarily have identical diameters.

[0084] When the discs or walls 136, 138 comprise arrangements or recesses around an orifice 192, 194, these arrangements and recesses are generally symmetrical with respect to a plane passing through the X axis and the Y axis of this orifice. This is particularly the case for the slots 180a.

[0085] In [Fig.6] for example, it can be seen that the slots 180a are arranged symmetrically with respect to the plane P passing through the axis X of the reducer and the axis Y of the orifice 192, 194 located between these slots 180a.

[0086] The wall 136, 138 of the disc may also comprise fixing holes 196. These holes 196 are intended to receive fixing elements such as screws, which make it possible, for example, to fix another part to the planet carrier s 113 such as a lubricating oil distributor for example.

[0087] When a plane H is drawn passing through the Y axes of two circumferentially adjacent orifices 192 or 194, it can be seen that the slots 180a are not cut by these planes, and neither are the fixing holes 196. It can also be seen that the internal 198 and external 199 peripheral edges of the walls 136, 138 of the discs are perfectly circular and centered on the X axis.

[0088] The invention proposes an improvement to a planet carrier for a mechanical reducer of an aircraft turbomachine.

[0089] This planet carrier can be of the monobloc type as illustrated in [Fig.2], or of the type cage and cage holder as illustrated in Figures 3 to 6. The foregoing descriptions in relation to Figures 2 to 6 may therefore be used to illustrate and describe the invention.

[0090] Furthermore, the planet carrier according to the invention can equip a reducer of a turbomachine as illustrated in [Fig.l]. The preceding description in relation to [Fig.l] can therefore also be used to illustrate and describe the invention.

[0091] Figures 7 and 8 illustrate a first embodiment of a planet carrier 213 according to the invention. This planet carrier 213 may be of the monobloc type or with a cage 220 and cage carrier.

[0092] In these figures, the elements already described in the above are designated by the same references increased by another hundred.

[0093] In these figures, the satellite carrier s 213 comprises:

[0094] - a first disc 236 centered on the X axis, called the first axis or central axis, and extending perpendicularly to this X axis, this first disc 236 comprising first bearing orifices 292 centered respectively on the Y axes, called bearing axes or second axes, which are parallel to the X axis and arranged around this X axis,

[0095] - a second disc 238 centered on the X axis and parallel and at a distance from the disc 236, this second disc 238 comprising second bearing orifices 294 which are respec- tively centered on the Y axes, and whose number is equal to the number of the first bearing holes 292, and

[0096] - bridges 296 which extend between the discs 236, 238 and connect them together, these bridges 296 being formed in one piece with the discs 236, 238.

[0097] In the figures, one of the two discs 236, 238 is visible but due to their similarities, they may have the same characteristics.

[0098] The first disc 236 is for example a front or upstream disc, and the second disc 238 is for example a rear or downstream disc, with reference to the position of the reducer in the turbomachine and to the flow of gases in the turbomachine.

[0099] The orifices 292, 294 are used to mount the satellites and in particular the satellite guide bearings, in the planet carrier 213. The bearings have longitudinal ends which are housed in these orifices 292, 294. The bearings are plain (hydrodynamic) or rolling bearings for example. These bearings are not shown in the figures.

[0100] At least one of the discs 236, 238 comprises an alternation of concave curved portions 298a, 299a and convex curved portions 298b, 299b on each of its peripheral edges 298, 299.

[0101] The convex curved portions 298b of the inner peripheral edge 298 and the concave curved portions 299a of the outer peripheral edge 299 are aligned radially with respect to the first axis X and extend respectively inside and outside the orifices 292, 294 of the disc 236, 238.

[0102] The concave curved portions 298a of the inner peripheral edge 298 and the convex curved portions 299b of the outer peripheral edge 299 are aligned radially with respect to the first axis X and extend between the orifices 292, 294 of the disc 236, 238.

[0103] The numbers of the concave curved portions 298a, 299a and convex curved portions 298b, 299b of the peripheral edges 298, 299 of the disc 236, 238 are equal to the number of orifices 292, 294 of this disc. This means that the number of concave curved portions 298a of the edge 298 is equal to the number of convex curved portions 298b of this edge, and is equal to the number of orifices 292, 294 of the disc. This also means that the number of concave curved portions 299a of the edge 299 is equal to the number of convex curved portions 299b of this edge, and is equal to the number of orifices 292, 294 of the disc.

[0104] In Figures 7 and 8, the following characteristics can be seen.

[0105] The convex curved portions 298b of the inner peripheral edge 298 may extend around the second Y axes of the orifices 292, 294 of the disc.

[0106] The convex curved portions 298b of the inner peripheral edge 298 may have an angular extent a about the first axis X, which is less than an extent angular [3 around the first axis X of the concave curved portions 298a of the inner peripheral edge 298.

[0107] The concave curved portions 299a of the outer peripheral edge 299 may have an angular extent y around the first axis X, which is less than or equal to an angular extent δ around the first axis X of the convex curved portions 299b of the outer peripheral edge 299.

[0108] a may be identical to y, at + / -30%, and preferably + / -10%.

[0109] [3 may be identical to ô, at + / -30%, and preferably + / -10%.

[0110] The apices of the convex curved portions 298b of the inner peripheral edge 298 may be located on a circumference C1 centered on the first axis X which has a first diameter DI.

[0111] The concave curved portions 298a of the inner peripheral edge 298 may be all and entirely located on the circumference CL

[0112] The apices of the concave curved portions 298a of the inner peripheral edge 298 may be located on another circumference C2 centered on the first axis X which has a second diameter C2.

[0113] Half of the difference between the second and first diameters D2, DI may be less than or equal to a minimum radial thickness El of material of the disc around its orifices 292, 294 and at the level of the internal peripheral edge 298. This thickness of material or this ligament of material is preferably reduced to the minimum necessary for the mechanical strength of the receiving orifice of the corresponding bearing.

[0114] The apices of the concave curved portions 299a of the outer peripheral edge 299 may be located on a circumference C3 centered on the first axis X which has a first diameter D3.

[0115] The convex curved portions 299b of the outer peripheral edge 299 may be all and entirely located on the circumference C3.

[0116] The apices of the convex curved portions 299b of the outer peripheral edge 299 are located on another circumference C4 centered on the first axis X which has a second diameter D4.

[0117] Half of the difference between the second and first diameters D3, D4 may be greater than or equal to a minimum radial thickness E2 of material of the disc 236, 238 around its orifices 292, 294 and at the level of the external peripheral edge 299.

[0118] The convex curved portions 298b of the inner peripheral edge 298 may have a radius of curvature XI which is less than the radius of curvature (which corresponds to D2 / 2) of the concave curved portions 298b of the inner peripheral edge 298.

[0119] The concave curved portions 299a of the outer peripheral edge 299 may have a radius of curvature X2 strictly less than the radius of curvature (which corresponds to D4 / 2) of the convex curved portions 299b of the outer peripheral edge 299.

[0120] The planet carrier 213 may have a maximum radial dimension H1 at the orifices 292, 294 of the disc 236, 238 which is less than a maximum radial dimension H2 of the planet carrier 213 between the orifices 292, 294 ([Fig.7]).

[0121] Figures 9 and 10 illustrate a second embodiment of a planet carrier 313 according to the invention. This planet carrier 313 may be of the monobloc type or with a cage 320 and cage carrier.

[0122] In these figures and the following ones, the elements already described in the above are designated by the same references increased by a new hundred.

[0123] In these figures, the satellite carrier s 313 comprises:

[0124] - a first disc 336 centered on the X axis and extending perpendicular to this X axis, this first disc 336 comprising first orifices 392 centered respectively on the Y axes which are parallel to the X axis and arranged around this X axis,

[0125] - a second disc 338 centered on the X axis and parallel and at a distance from the disc 336, this second disc 338 comprising second orifices 394 which are respectively centered on the Y axes, and the number of which is equal to the number of the first orifices 392, and

[0126] - bridges 396 which extend between the discs 336, 338 and connect them together, these bridges 396 being formed in one piece with the discs 336, 338.

[0127] In the figures, one of the two discs 236, 238 is visible but due to their similarities, they may have the same characteristics.

[0128] The first disc 336 is for example a front or upstream disc, and the second disc 338 is for example a rear or downstream disc, with reference to the position of the reducer in the turbomachine and to the flow of gases in the turbomachine.

[0129] The orifices 392, 394 are used to mount the satellites and in particular the satellite guide bearings, in the planet carrier 313. The bearings have longitudinal ends which are housed in these orifices 392, 394. The bearings are plain (hydrodynamic) or rolling bearings for example. These bearings are not shown in the figures.

[0130] The orifices 392, 394 of at least one of the discs 336, 338 are distributed in pairs. These are virtual pairs, the notion of a pair of discs qualifying the presence of two orifices side by side or circumferentially adjacent in the present application. The reference B designates for example a pair. The number of pairs of orifices of a disc 336, 338 is equal to N1, N being the number of orifices 392, 394 of the disc.

[0131] Each pair of orifices 392 or 394 thus comprises two circumferentially adjacent orifices.

[0132] The or each disc 336, 338 comprises, between each pair of orifices 392 or 394, a first through hole 400 which is cut by a first plane PI extending ra- dially with respect to the first axis X and located at equal distances from the orifices 392 or 394 of the pair, and which is cut by a second plane P2 passing through the second axes Y of these orifices /

[0133] The first plane PI is advantageously a first plane of symmetry for the hole 400. This first plane PI can furthermore be a plane of symmetry for the lights 380a.

[0134] The second plane P2 can also be a plane of symmetry for the hole 400.

[0135] Figures 10 to 13 illustrate several variant embodiments of the holes 400.

[0136] In [Fig.10], each of the holes 400 includes a radially inner edge 400a that is convexly curved about the first X axis, a radially outer edge 400b that is concavely curved about the first X axis, a first lateral edge 400c that is convexly curved about the second Y axis of a first of the holes 392 or 394 of the pair, and a second lateral edge 400d that is convexly curved about the second Y axis of a second of the holes 392 or 394 of the pair.

[0137] In [Fig.l 1], each of the holes 400 has an elliptical circular shape which includes a largest transverse dimension U1 extending along the first plane PL

[0138] In [Fig.12], each of the holes 400 has a rectangular shape with rounded corners.

[0139] In [Fig. 13], each of the holes 400 has a circular shape centered on the point or the intersection line W between the first and second planes PI, P2.

[0140] As can be seen in the variant of [Fig. 13], the or each disc 336, 338 may comprise, between each pair of orifices 392, 394, at least one additional through hole 401, 402 which is located radially above or below the first hole 400, and which is cut by the first plane PL

[0141] The first hole 400 and the or each additional hole 400a, 400b have the same shape and the same dimensions.

[0142] As can be seen in the drawings, the or each disc 336, 338 may comprise, between each pair of orifices 392, 394, at least one through-hole 380a, the first plane PI also being a plane of symmetry of this hole 380a.

[0143] The or each disc 336, 338 has a material thickness ZI measured in the radial direction relative to the first axis X, between an internal peripheral edge 398 of the disc, and the first hole 400, which is preferably less than a second material thickness Z2 measured in the same direction, between the first hole 400 and the light 380a.

[0144] The invention provides several advantages, including a reduction in the local stiffness of the planet carrier in order to reduce the aforementioned overload and the overall mass of the planet carrier and the reducer.

Claims

Claims

1. Planet carrier (213, 313) for a mechanical reducer (10, 110) of tur- aircraft machine (1), this planet carrier (213, 313) comprising: - a first disc (236, 336) centered on a central axis (X) and extending perpendicularly to this central axis (X), this first disc (236, 336) comprising first bearing orifices (292, 392) centered respectively on bearing axes (Y) which are distributed circumferentially around the central axis (X) and parallel to this central axis (X), - a second disc (238, 338) centered on the central axis (X) and extending parallel and axially at a distance from the first disc (236, 336), this second disc (238, 338) comprising second bearing orifices (294, 394) which are respectively centered on the bearing axes (Y), the number of second bearing holes (294, 394) being equal to the number of first bearing holes (292, 392), - bridges (296, 396) which extend between the first and second discs (236, 238, 336, 338) and connect them together,and the satellite carrier being characterized in that:, - at least one of the discs (236, 238, 336, 338) comprises alternating concave (298a, 299a) and convex (298b, 299b) curved portions on each of the inner and outer peripheral edges (298, 299) of the disc (236, 238, 336, 338), the convex curved portions (298b) of the inner peripheral edge (298) and the concave curved portions (299a) of the outer peripheral edge (299) being aligned radially with respect to the central axis (X) and extending respectively radially inside and radially outside the bearing orifices (292, 294) of the disc (236, 238), and the concave curved portions (298a) of the inner peripheral edge (298) and the convex curved portions (298b ... convex curved portions (298a) of the inner peripheral edge (298) and the convex curved portions (298b) of the outer peripheral edge (299) being aligned radially with respect to the central axis (X) and extending respectively radially inside and radially outside the bearing orifices (292, 294) of the disc (236, 238), and the convex curved portions (298a) of the inner peripheral edge (298) and the convex curved portions (29 convex curved portions (299b) of the outer peripheral edge (299) being radially aligned with respect to the central axis (X) and the numbers of the concave and convex curved portions (298a, 298b, 299, 299b) of the inner and outer peripheral edges (298, 299) of the disc (236,238) being equal to the number of bearing holes (292, 294) of this disc (236, 238), and / or, - the bearing orifices (392, 394) of at least one of the discs (336, 338) are distributed in pairs, each pair of bearing orifices (392, 394) comprising two bearing orifices (392, 394) circumferentially adjacent, the or each disc (336, 338) comprising pairs of bearing holes (392, 394) comprising, between each pair of bearing holes (392, 394), a first through hole (400) which is intersected by a first plane (PI) extending radially with respect to the central axis (X) and located at equal distances from the bearing holes (392, 394) of the pair, and which is intersected by a second plane (P2) passing through the bearing axes (Y) of this pair of bearing holes (392, 394), the first plane (PI) being a first plane of symmetry for the hole (400).

2. A planet carrier (213) according to claim 1, wherein the convex curved portions (298b) of the inner peripheral edge (298) extend around the bearing axes (Y) of the bearing holes (292, 294) of the disc (236, 238).

3. A planet carrier (213) according to claim 1 or 2, wherein the convex curved portions (298b) of the inner peripheral edge (298) have an angular extent (a) around the central axis (X), which is less than an angular extent (|3) around the central axis of the concave curved portions (299a) of the inner peripheral edge (299), and / or - the concave curved portions (299a) of the outer peripheral edge (299) have an angular extent (y) around the central axis (X), which is less than or equal to an angular extent (d) around the central axis of the convex curved portions (299b) of the outer peripheral edge (299).

4. A planet carrier (213) according to one of claims 1 to 3, wherein the convex curved portions (298b) of the inner peripheral edge (298) have an angular extent (a) around the central axis (X), which is equal to + / -10% of an angular extent (ip) around the central axis (X) of the concave curved portions (299a) of the outer peripheral edge (299), and / or the concave curved portions (298a) of the inner peripheral edge (298) have an angular extent (|3) around the central axis (X), which is equal to + / -10% of an angular extent (ô) around the central axis (X) of the convex curved portions (299b) of the outer peripheral edge (299).

5. Planet carrier (213) according to one of claims 1 to 5, in which: - the apexes of the convex curved portions (298b) of the internal peripheral edge (298) are located on a circumference (Cl) centered on the central axis (Cl) which has a first diameter (Dl), and the apexes of the concave curved portions (298a) of the internal peripheral edge (298) are located on another circumference (C2) centered on the central axis (X) which has a second diameter (D2), the difference between the second and first diameters (D1, D2) being less than or equal to a minimum radial thickness (El) of material of the disc (236, 238) around its bearing holes (292, 294) and at the outer peripheral edge (298), and / or - the apexes of the concave curved portions (299a) of the outer peripheral edge (299) are located on a circumference (C3) centered on the central axis (X) which has a first diameter (D3), and the apexes of the convex curved portions (299b) of the outer peripheral edge (299) are located on another circumference (C2) centered on the central axis (X) which has a second diameter (D4), the difference between the second and first diameters (D3, D4) being greater than or equal to a minimum radial thickness (E2) of material of the disc (236, 238) around its bearing holes (392,394) and at the level of the external peripheral edge (299).,

6. A planet carrier (313) according to any preceding claim, wherein the second plane (P2) is also a plane of symmetry for the hole (400).

7. Planet carrier (313) according to one of the preceding claims, in which the or each disc (336, 338) comprising pairs of bearing holes (392, 394) comprises, circumferentially between each pair of bearing holes (392, 394), at least one additional through hole (401, 402) which is located radially above or below the first hole (400), and which is intersected by said first plane (PI).

8. A planet carrier (313) according to claim 7, wherein the first hole (400) and the or each additional hole (401, 402) have the same shape and the same dimensions.

9. Planet carrier (313) according to one of the preceding claims, in which the or each disc (336, 338) comprising pairs of bearing orifices (392, 394) comprises, circumferentially between each pair of bearing orifices (392, 394), at least one through-hole (380a), said first plane (PI) also being a plane of symmetry of this hole (380a).

10. A planet carrier (313) according to claim 9, wherein the or each disc (336, 338) has a material thickness (Zl) measured radially relative to the central axis (X), between a peri- internal spherical disc (336, 338), and the first hole (400), which is less than a second material thickness (Z2) measured in the same direction, between the first hole (400) and the lumen (380a).

11. Mechanical reducer (10, 110) for an aircraft turbomachine, comprising a planet carrier (213, 313) according to one of the preceding claims, the reducer further comprising: - a sun (11) which is centered on the central axis (X) and which is mounted between the discs (236, 238, 336, 338) of the planet carrier (213, 313), - satellites (12) which are centered on the bearing axes (Y) and mounted between the discs (236, 238, 336, 338) of the planet carrier (213, 313), the satellites (12) being guided in rotation by bearings (8) housed respectively in the first and second bearing orifices (292, 294, 392, 394) of the discs (236, 238, 336, 338), and - a crown (14) being centered on the central axis (X) and extending around the sun (11) and the satellites (12), the satellites (12) being meshed with the sun (11) and the crown (14).

12. Turbomachine (1), in particular for an aircraft, comprising a reducer (10, 110) according to claim 11.

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